What is the name of Ariel's fish friend?

Ariel’s fish friend in The Little Mermaid is named Flounder.

Flounder is a yellow-and-blue tropical fish and Ariel’s closest companion in the 1989 animated film. Despite his name, he is not a flatfish; the character resembles a small tropical reef fish, often identified as resembling a royal angelfish. His nervous reactions provide comic contrast to Ariel’s adventurous personality, especially when they explore dangerous wrecks and forbidden human objects.

Flounder is more than comic relief. He supports Ariel’s fascination with the human world and remains loyal when her choices create trouble with King Triton and Ursula. Along with Sebastian, he helps Ariel after Ursula transforms her into a human. He also appears at the story’s climax and celebrates Ariel’s marriage to Eric.

Scuttle is a separate character: a seagull who claims expertise about human objects but frequently gives them incorrect names. Sebastian is Ariel’s crab companion and Triton’s adviser. “Guppy” is not Flounder’s name in the original film, although the prequel television series later gives the character an alternate real name.